Equipment for water heater

ABSTRACT

The invention relates to an equipment to be used in a gas-fired water heater which equipment contains a combustion chamber ( 2 ) and a heat exchanger ( 1 ). Accordingly the combustion chamber ( 2 ) is made of a ceramic material and provided with slots ( 3 ) for crossing the heating elements ( 4 ) of the heat exchanger ( 1 ) through the opposite walls ( 5,6 ) of the combustion chamber ( 2 ).

[0001] This invention relates to an equipment to be used in a gas-fired water heater which equipment contains a combustion chamber and a heat exchanger and in which equipment the heat exchanger and the combustion chamber are made of different materials.

[0002] A gas-fired water heater is usually used in heating water for sanitary matters in a household for daily needs. The gas-fired water heater is constructed to heat water as quickly as possible. This is because when a person opens the faucet of hot water, the heater starts to operate for heating the water. It is obvious that this kind of a system does not take too long in order that the system is practical for a person who needs to take for instance a hot water shower. Further in order to eliminate the risk of boiling for the water tubes the operation of the water heater is stopped just after the use of water is stopped by closing the faucet. In many cases the space for the gas-fired water heater is substantially small and, therefore, the gas-fired water heater has to be small enough to fit into the space reserved. Because the space reserved is small and usually the person living for instance in an apartment provided with the gas-fired water heater can move during the operation of the gas-fired water heater very close to the gas-fired water heater, it is very important that the external surfaces of the gas-fired water heater are also during the operation in a temperature low enough to prevent burns.

[0003] The object of the present invention is to eliminate some drawbacks of the prior art and to achieve a new and more practical equipment for a gas-fired water heater which equipment contains a combustion chamber and a heat exchanger and in which equipment the combustion chamber and the heat exchanger are made of different materials and that the combustion chamber and heat exchanger are fixed together. The essential features of the invention are enlisted in the appended claims.

[0004] In accordance with the present invention the combustion chamber in the equipment for a gas-fired water heater is made of insulating material, such as ceramics, and the heat exchanger is at least partly made of metal, such as copper or aluminium. The combustion chamber and the heat exchanger are fixed together. Therefore, the combustion chamber is provided with slots and the heating elements in the heat exchanger are crossing the opposite walls of the combustion chamber through these slots. The collectors in the heat exchanger which collectors are used to connect the separate heating elements together are positioned outside of the walls of the combustion chamber.

[0005] The combustion chamber of the present invention is advantageously made of one piece of an insulating material. The insulating material is made of ceramics, which can be ceramic fibre, heat resistant mortar or the like. In the combustion chamber gas is burnt and the hot gases from the combustion are conducted towards the heating elements of the heat exchanger. When using an insulating material the external surface of the combustion chamber is kept under a range of the temperature, which is essentially lower than using non-insulating material. In the preferred embodiment of the invention the combustion chamber is shaped so that the hot combustion gases are conducted upwards and thus the heating elements of the heat exchanger are installed in the upper part of the combustion chamber. In order to make more effective the influence of the hot gases to the heating elements of the heat exchanger the shape of the combustion chamber is such that the cross-section of the combustion chamber will advantageously decrease towards the upper part of the combustion chamber. The cross-section of the combustion chamber is advantageously rectangular.

[0006] In order to fix the heating elements of the heat exchanger to the combustion chamber in the preferred embodiment of the invention the upper parts of two opposite walls of the combustion chamber are provided with slots wherein the heating elements of the heat exchanger are installed. The slots in both walls are advantageously even in the width. The slots in one wall are positioned to each other so that the distance between two adjacent slots is essentially the same. The slots in the two walls are formed so that the heating elements of the heat exchanger can be installed essentially transversely to the two other opposite walls of the combustion chamber. The slots can be formed advantageously to the walls so that the two walls are provided with projections in the upper parts and the slots are positioned between these projections. The slots can be formed also to the walls so that the two walls are just provided with the slots. When using the projections for the slots the heating elements of the heat exchanger are installed above the level formed by the two other walls without the slots. When using the slots without any projections the heating elements of the heat exchanger are installed under the level formed by the two other walls without the slots.

[0007] The heat exchanger of the present invention contains heating elements, which are crossing the walls of the combustion chamber through the slots, and two collectors on the opposite walls of the combustion for connecting the separate heating elements together. The part of a heating element, which is positioned between the walls of the combustion chamber, is under the influence of the hot combustion gases. The heating elements are advantageously on their external surfaces provided with at least one fin on each element and on at least one part of the surface of each element. The fins are installed at least on that part of each element, which is positioned between the walls of the combustion chamber. The fins are advantageously manufactured of a corrugated metal strip, which is soldered or brazed on the external surface of a heating element. Thus two adjacent heating elements have a common fin between themselves so that the corrugated fin is soldered or brazed alternately to each heating element. The metallic material for the corrugated strip is advantageously copper or a copper alloy, aluminium or an aluminium alloy. The purpose of the fins is to exchange heat from the hot combustion gases to the metal of fins and further to conduct that heat to the metal of the heating element. The fins will also prevent the deformation of the heating elements in case of possible overpressure as well as the fins keep the desired distance between the heating elements.

[0008] The heating elements of the present invention are made of oval metal tubes, which are installed in the slots of the combustion chamber advantageously so that the flat parts of the oval tubes are positioned essentially vertically. The oval tubes are arranged in the slots in one level or in multi level depending on the needs to heat water. The oval tubes are provided with fins in their flat surfaces so that the fins have contact with two adjacent flat oval tubes.

[0009] One heating element of the present invention is connected to another heating element by the collectors, which are installed outside the walls of the combustion chamber provided with the slots. The collectors can be made of many different materials; both metallic as copper or a copper alloy, aluminium or an aluminium alloy, steel and non-metallic materials as polyamides, polybuthilen. The collectors will in one side form a continuous flow for the water to be heated and in another side at least one of the collectors is provided with at least one connecting element, which leads the water to be heated into the heat exchanger, and at least one of the collectors is provided with at least one connecting member, which leads the heated water away from the heat exchanger to be used in a desired manner.

[0010] When operating the equipment of the invention gas to be burnt in the combustion chamber is lead through a gas pipe into the combustion chamber and the hot exhaust gases from the combustion are flowed towards the heating elements in the upper part of the combustion chamber. Inside the heating elements water to be heated is flowed and depending on the construction of the collectors which direction water will be flowed in one individual heating element.

[0011] The invention is explained in more detail below, with reference to the appended drawings, where

[0012]FIG. 1 shows a preferred embodiment of the invention, seen in a side-view illustration, and

[0013]FIG. 2 shows a detail of the preferred embodiment of FIG. 1.

[0014] In accordance with FIG. 1 and FIG. 2 in the equipment for a gas-fired water heater the heat exchanger 1 is fixed to the combustion chamber 2 made of heat resistant mortar by slots 3 in the upper part of the combustion chamber 2. The oval tubes 4 made of copper and operating as heating elements of the heat exchanger 1 are crossing the opposite walls 5 and 6 of the combustion chamber 2 by means of the slots 3 so that the flat parts of the oval tubes 4 are positioned substantially vertically. The oval tubes 4 are provided with corrugated copper fins 11 brazed on the flat parts of the oval tubes 4 and the fins 11 are sized so that one individual fin 11 will reach alternatively two adjacent oval tubes 4. The oval tubes 4 are connected by the collectors 7 and 8, which are respectively installed outside the walls 5 and 6 of the combustion chamber 2. The collector 7 is provided with a connecting member 9 in order to lead water to be heated into the heat exchanger 1 and with a connecting member 10 in order to lead the heated water away from the heat exchanger 1. 

1. Equipment to be used in a gas-fired water heater which equipment contains a combustion chamber (2) and a heat exchanger (1), characterized in that the combustion chamber (2) is made of a ceramic material and provided with slots (3) for crossing the heating elements (4) of the heat exchanger (1) through the opposite walls (5,6) of the combustion chamber (2).
 2. Equipment according to claim 1, characterized in that the slots (3) are positioned in the upper part of the combustion chamber (2).
 3. Equipment according to claim 1, characterized in that the heating elements (4) of the heat exchanger (1) are metallic oval tubes positioned substantially vertically in the slots (3) of the combustion chamber (2).
 4. Equipment according to claim 3, characterized in that the metallic oval tubes (4) are provided with fins (11) made of corrugated strips between the opposite walls (5,6) of the combustion chamber (2).
 5. Equipment according to claim 4, characterized in that the fins (11) are soldered on the flat parts of the metallic oval tubes (4).
 6. Equipment according to claim 4, characterized in that the fins (11) are brazed on the flat parts of the metallic oval tubes (4).
 7. Equipment according to claim 1, characterized in that the heating elements (4) are connected to each other by collectors (7,8) installed in the both ends of the heating elements (4).
 8. Equipment according to claim 7, characterized in that the collectors (7,8) are positioned outside of the walls (5,6) of the combustion chamber (2). 